Ventilating the interior of buildings is highly desirable and essential wherever living creatures or plants are being maintained. For example, the interior conditions must be controlled in buildings used for warehousing or industrial storage, for the raising of vegetables and plants or for raising poultry or livestock. For those buildings where living creatures are being raised, proper interior ventilation is essential to their good heath. During the winter, buildings will most likely be cool and damp if the building is located in the northern climates. In the summer, the interior of the building will likely be hot and humid. Ventilation is a process to control the temperature, humidity and gases within the building, and with controlled ventilation, an improved environment can be maintained.
An ongoing problem in such buildings is to maintain a proper interior temperature, especially where the building houses livestock or poultry. Excessive heat or cold in the building can adversely affect the health of the live animals being housed. Typically, shutters of various designs are used in cooperation with ventilating fans to exhaust air from the interior of the buildings. However, most traditional shutters allow outside air to leak into the building. Leakage of outside air into the building increases heating costs during cold exterior temperatures, since more fuel is required to maintain a desired condition. During times of extreme high temperatures outside the building, movement of air from the interior of the building is also essential to maintain improved conditions inside the building.
There are known and used numerous designs of air ventilating units that can be mounted on the walls of a building to control the flow of air exiting the building. These units typically contain a shutter unit having pivoted louvers moveable from an open to a closed position. These louvers operate automatically in response to the negative or positive pressure created in the building by exhaust fans. However, with known air ventilating units of the automatic type, the louvers often do not seal completely, thus allowing outside air to leak into the building. Moreover, the louvers sometimes will flutter or flip over and stick open allowing outside air to enter the building. There is therefore a need for an improved air ventilating unit having multiple louvers which when mounted in the wall of the building will provide an airtight unit, resulting in minimal air leakage with minimal heat loss or cold air entering the building where installed.